The present invention relates to an air shutoff valve, for example, to prevent uncontrolled runaway of the engine.
Diesel engines, in the presence of combustible gases in the atmosphere, occasionally enter a runaway condition in which the engine, without a proper device to mitigate this problem, can enter an uncontrolled acceleration. In this condition, the engine experiences overspeed and, if not stopped, the engine can reach speeds that can result in destruction and/or catastrophic engine failure, and personal injury. There are a number of causes of runaway including, for example, a faulty engine governor, engine overheating or the ingestion of unregulated hydrocarbons into the combustion chamber through the intake air. Such hydrocarbons may be from an external source such as airborne gas, or from the engine itself due to a malfunction such as failure of turbocharger oil seals.
A conventional way to stop a diesel engine is to stop the flow of fuel to the combustion chamber. However, an alternate method must be employed to stop a diesel engine in the event of runaway. The most common method, used for many years, involves blocking the air supply to the combustion chamber of the engine. Once deprived of oxygen, the runaway ceases. Accordingly, safety valves which cut off the air supply to the engine have been developed to shut off the engine in such a situation.
One type of shut-off valve placed in the air intake to the engine employs a swing gate valve that is spring biased to be in a closed position that blocks air supply to the combustion chamber. The spring loaded valve is held in an open position by a trip mechanism that is manually cocked to hold the valve in the open position. A solenoid or by other appropriate device may be used to trip the trip mechanism to close the valve. When in the open position, there is an unobstructed air supply to the engine. Upon runaway, the device is engaged (or disengaged), and the valve snaps into its closed position, thus cutting off the air supply to the combustion chamber, thereby starving the engine of oxygen such that the engine stalls.
Shutoff valves used in the past were susceptible to damage from high vibration loads and excessively high temperatures. The present invention provides improvements to past designs and provides a valve capable of experiencing higher vibration and temperature.
All references cited herein are incorporated herein by reference in their entireties.